The roll shaft of the carrying system in the continuous casting equipment is bent, in accordance with passing of a work, such as a high temperature slab, or the like. Accordingly, both ends of the roll shaft are supported by a self-aligning bearing. As the self-aligning bearing for supporting the roll shaft mentioned above, there is employed a spherical roller bearing having a spherical roller, a cylindrical roller bearing with aligning ring having an outer ring, in which an outer peripheral surface is formed in a spherical shape, or the like. The cylindrical roller bearing with aligning ring can increase a load rating.
The roll shaft is structured such as to extend in an axial direction, in accordance with the passing of the high temperature work, and contract in the axial direction at the time of shutdown of an operation. Accordingly, it is necessary to position one end of the roll shaft in an axial direction and it is necessary to make another end of the roll shaft in a free state capable of expanding and contracting in the axial direction.
First, the structure is made such that the self-aligning bearing used in the one end side, that is the fixed side of the roll shaft is constituted by a single row cylindrical roller bearing with aligning ring, a flange is provided in both ends of inner and outer rings in the axial direction, and the cylindrical roller is positioned by each of the flanges in the axial direction.
The structure is made such that the self-aligning bearing used in another end side, that is, a free side of the roll shaft mentioned above is constituted by a single row cylindrical roller bearing with aligning ring, a flange is provided in both ends of any one of the inner and outer rings in the axial direction, another thereof is formed with no flange, and cylindrical roller is allowed to displace in the axial direction.
In the case that the self-aligning bearing in the fixed side mentioned above is constituted by the cylindrical roller bearing with aligning ring, the outer peripheral surface of the outer ring is formed in a spherical shape. Accordingly, a thickness of the outer ring in both ends in the axial direction is reduced, and a strength of the flange tends to be reduced. In order to secure a sufficient strength of the flange, it is necessary to increase a width of the flange in the axial direction and a thickness of both ends of the outer ring in the axial direction. However, in order to achieve the increase of width and thickness, it is necessary to increase an outer diameter of the outer ring as well as increasing an entire width of the outer ring in the axial direction. Accordingly, an outer shape of the self-aligning bearing is large-sized, and it is unavoidable to change design of an axle box.
However, in the case of restricting the entire width and the outer diameter of the outer ring in the axial direction so as not to change the design of the axle box, it is unavoidable to make an inner diameter of the outer ring small as well as to shorten a size of the cylindrical roller in the axial direction, resulting in lowering a load rating.
Taking the matters mentioned above into consideration, an object of the present invention is to improve a load rating and life of a self-aligning bearing, which positions one end of a rotation shaft axially expanded and contracted thermally, in an axial direction, without making an outer size larger.